Double-layer capacitors with liquid electrolyte and electrodes made of various materials having large specific surface are known in the art (e.g. U.S. Pat. No. 4,313,084 of 1982 and FRG Patent 3,210,420 of 1983). Best results are attained when using various activated carbons as the material of electrodes. Specific capacity of such capacitors exceed 2 F/cu.cm, while use of aprotic electrolytes enables their working voltage to be increased up to 2 or 3 V (see U.S. Pat. No. 4,697,224 of 1987; Nat. Tech. Report, 1980, 26 # 2, pp. 220-230).
However, use of carbonic materials and organic solvents ensures against obtaining high power characteristics of double-layer capacitors that are sometimes necessary, due to high internal resistance caused by low conductance of carbon and electrolyte. Increased charge/discharge current values of double-layer capacitors is attained by further improvements in construction of capacitor electrodes due to, e.g., the use of electrically conducting binder additives and of fibrous carbonic materials (see Carbon, 1990, 28 # 4, pp. 477-482; Radio-Fernsehen-Elektron, 1990, 39 # 2, pp. 77-800).
The most closely pertinent to the present invention in terms of its technical essence and the attainable effect is a double-layer capacitor having two polarizable electrodes made of activated carbon fiber (see W. Hallop et al. Low Cost Supercapacitors. Third International Seminar on double-layer capacitors and similar energy storage devices. Florida, 1993).
However, the electrical energy that can be stored by such capacitors are not sufficient for such applications as power sources for electric vehicles.